1 Field of the Invention
The present invention relates to a fuel cell, and more particularly to a fuel cell including a solid electrolyte layer, an oxygen electrode attached to one face of the electrolyte layer, a fuel electrode attached to the other face of the electrolyte layer and a conductive separator provided to be electrically connected with the oxygen electrode.
2 Description of the Prior Art
In a known flat plate type fuel cell of the above-noted type, as illustrated in FIG. 15, an oxygen electrode 2 (or a fuel electrode 3) or a separator 4 integrally forms a plurality of ribs 7 thereon for sectioning into a plurality of flow passages an oyxgen-containing gas flow passage 'a' (or a fuel flow passage 'g') between the oxygen electrode 2 (or the fuel electrode 3) and the separator 4. Then, as the oxygen electrode 2 (or the fuel electrode 3) and the opposing separator 4 are connected with each other through the plurality of ribs 7, the electricity flow passage between the electrode 2 or 3 and the conductive separator 4 may be enlarged in area.
Incidentally, the separator 4 functions not only as a sectioning means for sectioning the oxygen-containing gas flow passage 'a' (or the fuel flow passage 'g') into a plurality of passages but also as a cell terminal for obtaining electric current from the oxygen electrode 2 (or the fuel electrode 3) facing the oxygen-containing gas flow passage 'a' (or the fuel flow passage 'g'). Reference numeral 1 in FIG. 15 denotes an electrolyte layer.
However, if the oxygen electrode, fuel electrode, separator and the electrolyte layer are formed respectively of a thin plate element or a film element (a very thin film having a thickness in the order of some microns), the cell construction becomes extremely minute and complicated, whereby a very high manufacturing precision will be needed. Then, if the above-described construction is employed for such case, it is technically very difficult to form the plurality of ribs integrally with the electrode or the separator so that all the ribs may provide proper electrical connection. Therefore, this conventional construction has often proved infeasable such case.
Further, when the fuel cell is under operation for electricity generation, there occurs thermal strain between the oxygen electrode (or the fuel electrode) and the separator because of the rigidity of the construction. Then, again if the oxygen electrode, fuel electrode, separator and the electrolyte layer are formed respectively of a thin plate or film element to make up the conventional construction and the oxygen or fuel electrode and the separator are rigidly connected with each other through the ribs, thermal strain acts on the thin and weak plate or film elements, whereby quality is reduced, hence, performance deterioration or even damage in the cell construction occurs.
With view to the above-described shortcomings of the prior art, the primary object of the present invention is to provide an improved fuel cell free from the above-described problems even if its structure elements such as the oxygen electrode, fuel electrode, separator and the electrolyte layer are formed respectively of a thin plate or film element.